It has been reported that a culture supernatant of a lactic acid bacterium, i.e., a culture obtained by inoculating a lactic acid bacterium into a culture medium mainly containing milk as a principal component, contains a component having an effect as an external preparation for the skin. For example, it has been reported that a culture supernatant of a lactic acid bacterium has an antioxidative effect and a photoprotective effect (Patent Document 1, and Non-Patent Documents 1 and 2). Further, such a culture supernatant has been known to have an inhibitory effect on the formation of wrinkles (Patent Document 2), and it has also been known that in a lactic acid bacterium extract, a component having a cell proliferative effect is contained (Patent Document 3).
However, since there are a lot of lactic acid bacterial species, it is predicted that there are a wide variety of active ingredients contained in such a culture supernatant. Further, in order to use such a component as an active ingredient of a cosmetic or an external preparation, it is advantageous to select and use a portion having a particularly high activity according to the intended purpose, and therefore, it has been demanded that culture supernatants of lactic acid bacteria and lactic acid bacterial extracts be studied more to detect a component having a more potent effect.